Method for the manufacturing of hollow bodies of circular cross section having entrance openings



y. 16 1 9. J. SCHMIDT l.720,968

- METHOD FOR THE MANUFACTURING OF HOLLOW BODIES OF CIRCULAR CROSS SECTION HAVING ENTRANCE OPENINGS Filed May 12, 1927 Patented July 16, 1929.

UNITED STATES PATENT OFFICE.

JULIUS SCHMIDT, 0F FRANKFORT-ON-THE-MAIN, GERMANY.

METHOD FOR THE MANUFACTURING 0]? HOLLOW BODIES OF CIRCULAR CROSS SECTION HAVING ENTRANCE OPENINGS.

Application filed May 12, 1927, Serial No. 190,950, and in Germany June 29, 1927.

This invention relates to a method of making hollow bodies of circular cross section having openings left therein, and particularly cylindrical bodies of irregular cross-section such as, for example side-cars of motor-cycles.

In contrzulistinetion to a previous method of building bodies utilizing band-shaped strips of veneer which are. placed cross-wise the one over the other and glued together it is the object of the present invention to employ a binding element in the building operation which will readily adapt itself to irregular curvatures and which when glued to a base is not subject to warping as would be the case when the band shaped strips of veneer above referred to are employed.

The method of building hollow bodies according to the invention consists in fitting strips of wood around a last-shaped body, winding a rope of fibrous substance over and gluing it to said strips. placing an outer layer of wooden strips on the coiled rope and finally binding said outer layer by coiling a wire rope around and subsequently removing the wire rope after the hollow body has dried.

An embodiment of the invention is shown in the aocom anying drawings. in which:

Figs. 1 am 2 show in side elevation partly in section and in end view respectively the last-like form.

Fig. 3 shows the hollow body partly cut away so that the several layers are visible of which the body is composed.

Fig. 4 shows in side elevation the finished hollow body for a side car.

Fig. 5 shows in vertical section the front end of the finished hollow body.

Fig. 6 shows in cross section the several superposed layers during the manufacturmg.

Referring to the drawing, 1 are rings which, as shown in Figs. 1 and 2, are joined to form a last for the hollow body to be made. Two end disks 2 of the form will preferably remain in the hollow body and they are pressed against the rings 1 by means of a longitudinal rod 4. In order to securely hold the rings 1 in their mutual position pins- 5 are preferably inserted into the adjacent faces of said rings. The rings are of such thickness that they can be easily removed through the entrance opening 6 (Fig. 4) of the finished body. The lastlike. form is rotatably mounted as shown in Figs. 1 and 2 in a bracket 7, and it is advisable to mount upon the rod 4 a belt pulley, by means of which the last like form can be intermittently and slowly rotated.

After the outer surface of the last like form, as shown in Figs. 1 and 2 has been well greased, long boards 8 of wood are put onto this form and fixed in a suitable manner. The wood boards 8 must taper towards both ends. Over this layer 8 of wood boards a. rope 9 of fibrous material is wound in spirals. The form is slowly rotated on this occasion. Either the rope 9 is impregnated with glue or the layer 8 is painted with glue. The rope 9 does not only press the wood boards 8 upon the form, but it forms at the same time an elastic and tough intermediate layer between the inner layer of wood 8' and the outer layer of wood 10. Instead of the rope of fiber. strips of wood might be wound around the layer 8. If pieces of strips are used they have to be fixed at least at the end or at the beginnin On this layer of rope 9 a layer 10 of wood boards is placed which correspond. as regards shape and construction. essentially to the Wood layer 8. For the outer wood layer 10 precious wood is preferably used as this layer forms the outer shell of the hollow body.

()n this outer layer of wood 10 which is fixed on the rope layer 9 by gluing, a wire cable 11 is wound in spirals, the last-like form being rotated on this occasion. This wire cable serves merely to securely hold the outer layer 10 in its position. After the wire cable has been wound around the hollow body from one end to the other, the hollow body is left to dry. If one does not want to use a wire cable 11 the several-wood boards of the layer 10 must be fixed on the support by means of clamps and rivets whereby however holes are produced which unfavorably influence the outer appearance. After the drying the wire cable 11 is unwound and the outer layer is finished. After the entrance opening 6 has been cut the rings 1 are removed through this opening. After the rod 4 has been removed the hollow body is ready and can be further prepared in any desired manner. The two holes at the ends of the hollow body are closed in any convenient manner.

Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is: v

A method of building hollow bodies of circular cross-section having openin s and the like, consisting in fitting strips 0 wood around a last-shaped body, winding a rope of fibrous substance over and gluing it to said strips, placing an outer layer of wooden 1 strips on the coiled rope and finally binding said outer layer by coiling a wire rope therearound and subsequently removing the wire rope after the hollow body has dried.

In testimony whereof I affix my signa- 15 ture.

JULIUS SCHMIDT. 

